A semiconductor integrated circuit used in mobile electronic equipment, such as a mobile telephone, is provided with a power on reset circuit (hereinafter, referred to as a POR circuit) for monitoring whether a power supply voltage obtained from a battery element, an input terminal, etc., is supplied stably.
The POR circuit is desired not to malfunction even in an unstable period of time during which a power supply rises, to detect a voltage with no delay, to operate at low power because the voltage is desired to be monitored at all times, etc. In order to realize these requests, various kinds of POR circuits have been proposed.